I. Field of the Invention
The present invention relates generally to human powered propulsion systems for watercraft. More particularly, this invention relates to a pedal-driven sculling paddle assembly that can be removably mounted upon a variety of small boats. Known relevant prior art may be found in U.S. Class 440, Subclass 24.
II. Description of the Prior Art
I have invented a new human-powered paddle system that may be easily mounted upon a wide variety of conventional watercraft. The system propels the boat by oscillating a bow-mounted paddle with cables driven by foot pedals. The system may be installed and operated without modification of the watercraft's structure. When installed, the system permits continued, unobstructed passenger access to substantially all of the watercraft interior.
A variety of prior art systems relating to human-powered watercraft exists. For example, known foot operated paddle systems most closely related to the concepts of this invention can be found in the patent records in U.S. Class 440, Subclasses 13, 21 and 24. The two most relevant prior art patents known to me comprise U.S. Pat. No. 3,095,850 issued Jul. 2, 1963, and U.S. Pat. No. 4,960,396 issued Oct. 2, 1990. The disclosures of the last-mentioned patents are hereby incorporated by reference.
The aforementioned patents disclose watercraft propulsion devices having a single paddle that is operated by a pair of cables. A foot-operated pedal arrangement tensions the cables. When pressure on one pedal exceeds pressure on the other, two basic paddle movements are produced. First, the paddle is rotated about its longitudinal axis every stroke to establish pitch. Secondly, for propulsion, the paddle is vigorously pivoted within a plane that is both parallel with the bow and generally perpendicular to the longitudinal axis of the watercraft. When a user alternates tension on the pedals, blade pitch is also alternated to preserve the selected direction of travel.
Another blade movement results if both foot pedals are pressured at once. A cable-controlling "donut" flips over in response to the sum of the pressure from both cables and reverses the alternate blade pitch movements established by rotation of the blade about its longitudinal axis. Thus, when both foot pedals are pressed in unison, the total cable pressure reverses the direction of travel. As long as pressure on one foot pedal exceeds the non-zero pressure on the other pedal, the alternate power strokes that follow reverse the craft.
In addition to the paddle movements mentioned above, U.S. Pat. No. 4,960,396 discloses paddle structure characterized by a "break-away" motion. In this case, unintended impact with submerged obstacles can nondestructively dislodge the blade from its normal orientation to prevent paddle breakage.
U.S. Pat. No. 4,353,703 issued Oct. 12, 1982 discloses a foot-operated, marine propulsion system that can be retrofitted to small watercraft. A pair of spaced-apart paddles are driven by human power. U.S. Pat. No. 3,680,522 Aug. 1, 1972 depicts a pedal-powered boat drive mechanism with a drive shaft. Other prior art known to me comprises U.S. Pat. Nos. 4,323,352; 4,345,903; 3,467,049; 4,172,426; 4,231,309; 3,056,977; 3,038,435.
No known prior art system is adapted to be removably installed upon existing watercraft. In other words, modifications to the existing watercraft structure are always required. Known systems often require elaborate means for attaching them to the watercraft superstructure, and in many cases the systems are severely limited as to boat size ranges with which they may be used. Further, many prior systems tend to clutter up the boat interior, adding inconvenient obstructions to the boat occupants.
Systems such as those disclosed in U.S. Pat. Nos. 3,095,850 and 4,960,396 discussed above have numerous other disadvantages. One problem is that they may strain the bow of the boat. Typical smaller watercraft have somewhat flexible characteristics, and the stress of the normal tensioned drive pulleys and related apparatus can deform, if not break, the transom or bow of the watercraft. Also, when prior art devices are firmly attached to the boat interior, the resultant forces may be unevenly distributed. For example, a clamp firmly attached to a given area will apply too much force to a limited area, causing breakage or damage. Therefore operating forces developed by a viable system must be properly distributed upon the watercraft structure.
Often the drive cable is a problem. It is frequently noisy and difficult to adjust and position. Being of constant length, the system fails when the cables are too long, and the devices cannot be used at all when the cables are too short. No quick connection or quick adjustment means have hitherto been provided to adequately address the cable length problem inherent in such devices.
Another characteristic design problem relates to the method of reversing propulsion. The above-discussed Stolzer devices require the operator to pressure both pedals when reversing direction. Such added effort can fatigue some users, decreasing both range and speed.